The invention relates to a vane pump having an annular cam fixedly disposed in a pump housing and a rotor which is regionally surrounded by the annular cam and has axial slots. Vanes are radially displaceable in the slots and are guided by their radial outer margins on the annular cam. The vanes separate pump working chambers from one another in an annular space left radially between the annular cam and a rotor part surrounded by the annular cam. The rotor possesses, axially next to the annular cam, a further rotor part of large diameter which is at least equally as large as the maximum diameter of the annular cam relative to the rotor axis, the slots in the rotor part surrounded by or enclasped by the annular cam continue axially and in a radially outward direction into the further rotor part. On that end face of the rotor facing away from the further rotor part there is disposed an axial slide of annular cross-section, the outer contour of which corresponds to the inner contour of the annular cam and the inner contour of which corresponds to the circular outer contour of the rotor part enclasped by the annular cam. The axial distance between the further rotor part and the facing end face of the axial slide is adjustable, regions of the vanes being able to slide, according to the adjustment of the axial slide, axially into the slots in the further rotor part or axially out of these slots.
A corresponding vane pump is the subject of German Patent Document DE-A 20 61 385. A design of this type is advantageous insofar as the volumetric displacement of the pump is continuously variable by adjustment of the axial slide and the annular cam can have, in principle, any chosen cross-section, such that, when the pump is running, a good mechanical balance of the vanes moving in the radial direction and an extensive .compensation of the fluidic forces acting upon the rotor are made possible.
In pumps of this type, however, the guidance of the vanes is critical. The vanes according to German Patent Document DE-A 20 61 385, for instance, have to be guided in the radial direction between axially movable parts.
The same basically applies to a vane pump known from U.S. Pat. No. 1,659,753, in which the effective axial width of the pump working chambers is likewise variable.
In a vane pump known from German Patent Document DE-B 10 65 243, the pump working chambers of which exhibit a variable axial width, although the vanes are guided radially on rotor fixed parts, the annular cam must nevertheless be movably disposed.
In addition, as technological background to the vane pump, reference is also made to German Patent Document DE-A 41 20 757, in which there is represented a vane pump, the pump working spaces of which exhibit a non-variable axial width.
An object of the invention is now to provide a new vane pump of the type specified in the introduction, in which the movements of the vanes, in particular, are designed to proceed with high precision.
This object is achieved according to the invention by the fact that the vanes respectively comprise a vane-carrier part and a vane part, the vane-carrier part, which is axially retained between stationary parts on the end face of the rotor and is only radially movable, remaining in all radial settings within the slots and the vane part, which is guided radially on the annular cam and bears against the adjacent end wall of the axial slide, being guided axially displaceably on the vane-carrier part.
Based on the construction according to the invention, a particularly good guidance of the vanes is achieved. Since the vane-carrier parts, in their movements in the radial direction, are guided by stationary parts, any tilting movements about an axis perpendicular to the plane of the vane can be virtually fully precluded. This also simultaneously has the effect that the vane parts, which are axially displaceable in the vane-carrier parts, are likewise prevented from corresponding tilting movements, to be precise even when these vane parts, upon a correspondingly large adjustment of the axial slide in the direction of a low pump delivery, are forced with just a narrow lateral region against the annular cam.